Selecting a cupola – What size do I need?

A cupola is one of the most popular storage shed accessories.
Whether it be for added ventilation or simply curb appeal selecting the proper size cupola for your shed or barn is important. The following information will help you determine what size cupola you need for your outbuilding.

This guide to sizing your cupola is for storage sheds and relatively small barns however, much of this information can be used for larger buildings. If you would like our educated opinion on a size for a larger structure please feel free to comment here or send us an email and it would be our pleasure to assist you.

The first thing you need to do is measure your unbroken roof line. In most cases this is about or exactly the same as the length of the shed.
Unbroken roof line refers to the distance the roof line spans without deviating in elevation.

Next measure the width or depth of the storage shed assuming it does not have over sized eves or overhangs.

The last measurement and typically not included in most cupola size charts is the height of the building from ground to roof peak.

To begin: 1 foot of unbroken roofline equals 1.25 inches of cupola base. So if your structures unbroken roofline is 30 feet long then the cupola base width would be approximately 37.5 inches. With that said the height of the structure must also be considered.

The height of the structure upon which the cupola will be mounted is also a factor in determining size. If your structure is relatively short such as a ranch style home then it is a good idea to change the ratio you use to determine size: “1 foot equals 1 inch” is probably a good ratio. If the cupola will be going on a two story structure where the roof line is unbroken then the 1.25 inch per foot rule of thumb is the better option. If the cupola will be on a large/tall horsebarn etc. then using the 1.25″ per foot rule and then going one (or two) sizes larger may be a good idea.

The majority of cupola buyers now have all the information they need to make their purchase however there are other factors which some of you may need to take into consideration.

*Long and Skinny – Some buildings such as Single Bay Garages, Row Barns and Monitor Barns are long and narrow and therefore the cupola may need to be downsized.Imagine a 12′ wide by 36′ long single story, single bay garage. A 36″ wide cupola would look ridiculous on the roof (at least to most people). So you may want to downsize slightly. A 30″ cupola would probably look appropriate on this building.

*Very steep – When a cupola is installed the base of the cupola is cut to match the pitch of your roof. If the roof is say a 12/12 pitch the cupola will sit lower on the roof. In these cases you should be considering cupolas which are taller. A short cupola will only look shorter once mounted. Conversely, if you have a very shallow pitch like a 5/12 a very tall cupola will still look tall when mounted.

*Multiple cupolas – Larger structures or structures with “broken roof lines” in many cases will look better with more than one cupola as opposed to one very large cupola. “L” shaped houses sometimes look as if something is missing when only the main part of the house has a cupola. A single HUGE cupola on a large Riding Arena may seem lost. These are perfect examples of structures which will look better with multiple cupolas. Determining the size of these cupolas is a matter of taste however if it is an “L” shaped house for example use the 1 foot = 1 inch rule of thumb for each section of unbroken roof line. For a very large barn or Stable you may want to go a bit larger. In the case of a super large structure you may want to consider a large cupola in the center of the roof with 1 smaller cupola on either side centered between the main cupola and each gable end of the building (a total of 3 cupolas).

*Note – This is simply a guide. Many people like the look of an oversized cupola with windows and lighting while others would prefer something basic and less imposing.

If you are on the fence and not sure exactly what you would like on your shed visit a local retailer who offers cupolas. Most large storage shed retailers have several different size sheds on display with cupolas. It is much easier to make your selection when you have seen a similar size shed to yours with a cupola on top.

I would go with a cupola with a 37″-40″ base.
When purchasing your cupola be sure and ask if you will need an extended base due to the roof pitch. Extending the base (increasing the height of the cupola base to accommodate the cut for the pitch) should not add anything to the price.

If the sidewalls are about 7-8 feet tall I would suggest at least a 21″ up to a 24″ shed cupola (lower profile than a house cupola) if the roof does not come to a point.
If the hip comes to a point then I would suggest going with a 21″ shed cupola.